Jambs w



(ModeL) J. W. CAMPBELL.

' W001) SGREW.- v 1 A No. 246,368. Patented Aug. 30,1

UNITED STATES PATENT OFFICE.

JAMES W. CAMPBELL, OF BROOKLYN, NEW YORK.

woon-scnew.

,srnoxrrca'nofi forming part of Letters Patent No. 246,3 63, dated.August 30, 1881.

.\ Application mearebmr aaisai. (Model) To all whom it may concern:

Be it known that I, James W. CAMPBELL, of Brooklyn, in the county of Kings and State of New York, have invented a' certain new and useful Improvement in Wood-Screws, of which the following is a specification.

The principal object of my invention is to provide a wood-screw which may he coustructed so as to cutits own countersink without mas terially increasing its cost.

To this end the invention consists in a countersinking wood-screw having across the coni- 5 upon an enlarged scale to ing a "cutting-edge,

cal head a nick, the walls of which are mainly parallel, but of which walls each is divergent fromthe ot-her near one end, to givecleara-nce to the chips made by a cutting-edge'at the extremity ot' the straight wallopposite, theplanes ot the several sections of wall being all paralv or walls of the nick a are parallel throughout the greater part of their length, but diverge from each other at each end of the nick, the extremity of the straight side or wall b formand the divergent orchlique side or wall b giving clearance to the chips made by the opposite cutting-edge.

1n the sides of the head B are two notches, C, which are diametrically opposite each other at opposite ends of the nick,

Figure 1' reference designate correand the sides of v the notchesform coutinuations of the sides or walls b b of the nick, as clearly seen in Fig.

1. It will be observed that the walls I; b lie in planes which are all parallel with the longitudinal axis of the screw, although not paral lel with each other.

In screwing in the screw it is, of course, turned in the direction of the arrow, Fig. 2, and the outtting-edge of each wall 1) forms the countersink, while the oblique or divergent wall b afi'ords ample clearance for the discharge of chipsand shavings.

" The notch-es C may he very readily formed hyl two milling-saws of proper transversesectioual form, moving in lines parallel with the longitudinal axis of the screw and operating in conjunction with the nicking-saw, and when so formed the notches add very little to the cost of the screws. Inasmuch as only two notches are formed in the head, the conical bearingsurface of the head is very little impaired.

The most important merit of my invention consists in the facility with which the notches above described can be cut in the screw-head as compared with other notches cut or other wise formed in screw-heads to enable them to out their own countersink.

7 What I claim as my invention, and desire to secure by Letters Patent, is--' Acountersinklng wood-screw having a conical head with a nick the walls of which are mainly parallel, but of which walls each is di- '-vergent from the other near one end to give clearance to the chips made by the cuttingedge of the straight wall opposite, the planes of the several sections of wall being all parallel with the longitudinal axis of the screw,

. though not parallel with one another, substantially'as specifiedfi i J. W. CAMPBELL. Witnesses:

Fnznnx. HAYNES, A. (J. WEBB. 

